Transmission and fluid pressure controls



Sept. 18, 1956 w. B. HERNDON TRANSMISSION AND FLUID PRESSURE coNTRoLs 14 Sheets-Sheet l Filed Dec. 8, 1950 iii Snvenfor Gttornegs Sept. 18, 1956 w. B. HERNDoN TRANSMISSION AND FLUID PRESSURE CONTROLS 14 Sheets-Sheet 2 Filed Dec. 8, 1950 Gttornegs sept. 1s, 1956 w. B. HERNDQN 2,763,162-

TRANSMISSION AND FLUID PRESSURE CONTROLS Snentor Bg y - (Ittomegs Sept. 18, 1956 W. B. HE-RNDON TRANSMISSION AND FLUID PRESSURE CONTROLS Filed Dec. 8. 1950 14 `Sheets-Sheet 4 Sept. 18, 1956 w. B. HERNDON TRANSMISSION AND FLUID PRESSURE coNTRoLs 14 Sheets-Sheet 5 Filed Dec. 8, 1950 Sept. 18, 1956 w. B. HERNDON TRANSMISSION AND FLUID PRESSURE CONTROLS 14 Sheets-Sheet 6 Filed Dec. 8, 1950 Sept' 18, 1955 w. B. HRDON 2,763,162

TRANSMISSION AND FLUID PRESSURE CONTROLS Filed Dec. 8, 1950 14 Sheets-Sheet 7 nventor Sept. 18, 1956 w. B. HERNDON TRANSMISSION AND FLUID PRESSURE CONTROLS 14 Sheets-Sheet 8 Filed Dec. 8. 1950 W /M attorneys sept. 1s, 1956 14 sheets-sheet 9 Filed Dec. 8, 1950 Sept. 18, 1956 w. B. HERNDON TRANSMISSION ANO FLUID PRESSURE CONTROLS 14 Sheets-Sheet 10 Filed Dec. 8, 1950 lmventor (Ittornegs .SAM.

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Sept. 18, 1956 w. B. HERNDON TRANSMISSION AND FLUID PRESSURE CONTROLS 14 Sheets-Sheet 11 Filed Dec. 8, 1950 (Ittornegs Sept. 18, 1956 w. B. HERNDON 2,763,162

O TRANSMISSION AND FLUID PRESSURE CONTROLS Y Filed DBC. 8, 1950 14 Sheets-Sheet l2 L k Q 'g 5 Z'mventor Gttornegs Sept- 18, 1956 w. B. HERNDON 2,763,162

TRANSMISSION AND FLUID PRESSURE CONTROLS Filed Dec. 8, 1950 14 Sheets-Sheet 15 Bnventor Gttornegs Sept. 18, 1956 w. B. HERNDON TRANSMISSION AND FLUID PRESSURE CONTROLS Filed Dec. 8. 1950 14 Sheets-Sheet L4 Cttornegs TRANSMllSSll-UN AND FLUID PRESSURE CNTRLS Application December S, 1950, Serial No. 199,806

23 Claims. (Qi. '7d-645) The present invention relates to automatic transmissions, particularly for vehicles, and more particularly to those transmissions having friction, torque-sustaining members actuated by controlled fluid pressure supplied by pumps driven by the power and load shafting; in which the speed ratio ranges are selected by fluid pressure operated valving moved to various positions in accordance with variations in vehicle speed and in the torque demand app ied by the driver or operator to the engine power control.

The invention pertains further to transmission drive structures embodying plural step-ratio change mechanism, wherein plural paths of torque are established through separate torque-multiplying channels and their torques recombined in a novel gearing arrangement having unique means to obtain reverse drive.

it pertains in particular to a compound reverse gear arrangement wherein novel means are utilized to establish reverse torque, and in which the torque reaction force is applied to assist in the energizing of the friction member which sustains that force, and especial advantages obtain from the arrangement of the reverse gear elements and their torque-reaction supporting structures as will be understood further in detail in this specification.

Among the manifold advantages and special features of the invention disclosed herein are drive control structures which are commonly controlled with the transmission ratio controls, and which are made effective to brake the motion of the vehicle under given drive circumstances, controlled in part by the drive conditions, so as to provide a degree of safety or" operation superior to that obtainable in related braking controls now in general use.

A further useful feature is the provision herein of a fluid pressure ratio control system for the drive of the transmission which is effective when set for reverse drive to cause one of two friction torque-sustaining members to be first applied by the liuid pressure, prior to the iluid pressure application of the other of the said two members, the sequence of this application being controlled in part by the rise of pressure in the application of the first said member, and in part by pressure-responsive devices which provide a timing control to the application of uid pressure to the second of said members.

Another feature of novelty consists in the provision of a transmission control system including a parking brake mechanism having means for preloading the mechanism for actuation when the driver operable control valve is positioned for reverse condition of transmission operation, and including means responsive to system pressure for blocking the actuation of the parking brake mechanism whenever the system pressure exceeds a predetermined pressure.

Additional features of novelty are disclosed herein, consisting of a fluid pressure ratio control and actuation system having valving automatically moved by uid pressure for various required operations of selecting the actuation of a plurality of friction, torque-sustaining memnited States Patent O bers, and of graduating the action of said members; having manual valving operative to select initial forward or reverse drive, and having hydraulic interlock passages connected to withhold or set aside the automatic responses Y of certain of said automatically-moved valving and prevent such responses, while operating to permit the operation of certain others of said automatic Huid-pressure responsive valving such as the aforesaid timing devices.

The above-recited features of novelty appear herein, for the most part, in singular embodiments rather than in various moditications, it being understood that these features may be demonstrated by other structural forms `without departing from the teachings of the invention.

A further feature of novelty consists in the provision of a pump and circulatory system whereby working liuid directed first to a iiuid iiywheel structure and then to a step-ratio transmission mechanism for lubricating the latter, whereby oil heated in the fluid ilywheel structure is cooled by two separate heat-flow surfaces.

These and other novel features and objects of this invention will be apparent from the following specification and claims taken in conjunction with the accompanying drawings, in which:

Figures l and 2 are adjoined vertical sections of the transmission drive mechanism of the invention, to the same dimensional scale.

Figure 3 is a cross-section of the transmission taken at 3-3 of Figure 1, to show one of the servo pumps and the line pressure regulator valving, and to show the fluid pressure servo actuator device for the front unit reaction brake.

Figure 4 is a similar cross-section taken at 4 4 of Figure 2 to show the iiuid pressure servo actuator device for the rear unit reaction brake.

Figure 5 is a schematic control diagram of one form of tluid pressure actuation and control system, wherein the friction torque-sustaining members and their actuators of the preceding iigures are shown at the top of the drawing, the ratio control valving in the center, and the pump supply portion of the system, and the hydraulic governor at the bottom.

Figure 5a is an enlarged view of the control valving shown at the left hand side of Figure 5, to more clearly illustrate the valve details.

Figure 5b is an enlarged view of the control valving shown at the right hand side of Figure 5, to more clearly illustrate the valve details.

Figure 5c is an enlarged view of the check valve 136 of Figure 5, illustrating the liuid flow restricting ports of the valve and valve body.

Figure 6 is a similar control diagram to that of Figure 5, wherein some modiiication features appear, such as the use of throtfle-pedal-modulated line pressure and second speed automatic start, in combination with the special control features demonstrated in Figure 5.

Figures 7, 8 and 9 are part sections of the timing valve construction of Figures 5 and 6, used to stage the sequence of fluid pressure servo actuation of the friction members which sustain the reverse drive torque. The manual selector valve is shown in three successive positions, moved upward from the reverse control position of Figures 5 and 6, to show the relative displacements of the timing valve bosses and ports.

Figure 9 shows the timing valve in its full non-operating station, held out of action by the manual valve.

Figure i0 is a side view of the transmission casing of Figures l and 2 with the valving of Figures 5 and 6 shown in part, with the valve housing sectioned; with the mechanical external operator controls aligned for the required shift operations; and shows the coordinated braking mechanism as it appears with the cover-plate removed.

Figures 11 and 12 show the details of the braking mechanism controlled by the external control mechanism of Figure 10, the part section elevation view of Figure ll being in a parallel plane to the right hand portion of Figure 10, and the Figure 12 view being taken at 12-12 of Figure 11, at right angles to the Figures 10 and 11 Views.

Figure 13 is a cross-sectional view of the governor and its drive mechanism, the cross shaft drive appearing in Figure 2.

Figure 14 is a view of the drivers control mechanism for controlling the structures of Figure 10.

Figure 15 is a partially sectional view of a variable capacity pump and control therefore which may be substituted for the gear pump and pump control of Figure 5.

Figure 16 is a partially sectional view of the same variable capacity pump illustrated in Figure 15 and illustrating a modied pump control arrangement which may be utilized in place of the pump and pump control illustrated in Figure 6.

The drive structure of the transmission of the invention is shown in section in companion Figures 1 and 2. The engine shaft 1 is bolted to flywheel plate 2 fastened to drum 3 connected by vibration damper device 4 to hub 5 splined to hollow shaft 6, which is keyed to drive pump gear 7 (see Figure 3) of pump P, and formed at the right into drum 9 having internal gear teeth 10 meshing with planet gears 12 meshed with sun gear 11. The planets 12 are supported on spindles 13 of carrier 20 connected to shaft 21, the right hand portion 15 connected to the carrier being formed to accommodate clutch plates 165, mating with plates 166 rotating with drum 14 connected to sun gear 11. This gear group is referred to as the front unit, and is made operative by application of band 170 to drum 14 of sun gear 11, or by engagement of the clutch 165-166.

The right hand inner Wall of drum 14 is recessed to form an annular cylinder space 42 for clutch piston 41, fed by uid pressure in passage 139'.

The forward extension of hollow shaft 21 is splined to the hub of fluid flywheel rotor or impeller 22 facing rotor 23 to form a fluid turbine working space W. The hub 24 of rotor 23 is splined to the forward end of transmission shaft 25. The clutch 165-166 is disengaged by springs 19 supported in the left wall of drum 14.

' The pump P is built into the forward web of the transmission housing 99, and consists of drive gear 7 meshing with idler gear 8 supported in section 99a. It draws oil from sump S through passage 388 and delivers fluid under pressure to maintain the uid working space W filled, to furnish pressure lubrication to the system, and to supply the requirements of the transmission servo systems shown in Figures 5 and 6.

The casing web 991) divides the transmission radially, and supports the shafting as shown, while affording passage space for the fluid servo and lubrication feed connections.

In Figure 2 the gear group 26, 27, 28 is considered the rear unit, and shaft 25 is integral with sun gear 26 meshed with planet gears 28 supported on spindles 29 of carrier 30 integral with output or load shaft 50. Internal gear 27 meshes with planets 28 and is attached to drum 31 which is equipped with key bolts for clutch plates 167 mating with plates 168 keyed to drum 32 splined on the rearwardly extending portion of shaft 21.

The forward wall of drum 31 is recessed to form an annular cylinder space 37 for piston 36, and springs 332 serveV to disengage plates 166 and 167 when cylinder 37 is connected to exhaust.

The rear unit is operated to change the speed ratio by alternate application of band 40 to the drum 31 of annulus gear 27, or by engagement of clutch 166-167. The clutch engaging and holding fluidpressure is delivered by passage 216 to cylinder 37.

The gear unit at the extreme right of Figure 2 is for providing reverse rotation of shaft 50. A plate 51 is splined to the forward portion of sleeve 49 of sun gear 5S which gear 55 meshes with planet gears 54 supported on spindles 53 of carrier 52 splined to shaft 50.

The output drive mechanism at the right of Figure 2 consists of a driven shaft 50, the forward end of which is flanged to form the carrier 30 for the rear unit.

Reverse unit carrier 52 is splined to shaft 50, and has affixed planet spindles 53, and the forward half 52' of carrier 52 is fixed to speedometer and governor drive gear 53. The planet gears 54 on spindles 53 mesh with the sun gear 55, the extension 49 of which is splined to plate 51, and planets 54 also mesh with annulus gear 57 of drum 58 supported for axial movement on bearing sleeve 59, and for abutment against thrust washer 61.

Parking brake teeth 62 are cut on the periphery of the drum 58, and the drum carries a brake cone at the right, operable to be braked by piston 129 forcing it against backing cone 132 keyed to the housing 99.

The brake cone 130 is engaged when the manual selector 500 of Figure 14 is placed for reverse, and a pawl member 236 carries teeth 238 (see Figures 11 and 12) adapted to engage teeth 62 when the manual selector 500 is placed in reverse and the vehicle is standing still with the engine turned off as hereafter more particularly explained. When teeth 238 of pawl 236 engage teeth 62, the drum 58 is locked against rotation, this action providing a parking brake for the vehicle.

The wave-washer spring 63 seats against thrust washer 64 supported on carrier 52 and against the radial web of drum 58.

The teeth of the sun gear 55, planets 54 and annulus gear 57 are cut helically for running quietly, and for providing a torque thrust operable to apply a self-energized brake action to cone 130, when there is initial braking force applied by piston 129.

Assuming that the teeth of annulus gear 57 and planet gears 54 are cut with a right-hand helix angle, and that the effect of delivered torque to drum 31 and sun gear 55 applies rotation to the sun gear 55, for reverse drive of output carrier 52, the annulus gear 57 in attempting to rotate forwardly, meets the resistance of friction on the cone surfaces of cone 130 and elements 129 and 132. Because of the resultant thrust of the helix angle between the teeth of planet gears 54 and annulus gear 57, the annulus gear 57 receives a thrust to the left toward the forward end of the transmission and this trust is applied to cone 130 as a braking effort adding to the thrust applied by piston 129. This action compresses the wavy spring 63.

The design helix angle for these gears may be taken according to engineering standards, but it is preferred in the present disclosure to have the self-energizing brake force, lie between 18 and 30 per cent of the total cone braking force.

When the vehicle is decelerated during reverse drive, the self-energizing action is obviously reversed, and the annulus gear 57 endeavors to move to the right assisted by spring 63 into abutment with washer 61, while the piston 129 retains the iluid pressure actuation force on cone 130.

It will be seen that upon deceleration, such as occurs when the driver relaxes the engine accelerator and may apply the vehicle brakes, the device is ready to apply a reverse brake release force to the cone 130, the instant the fluid pressure which is holding the piston 129 applied, is released or exhausted.

This arrangement prevents slamming of the torquesustaining elements, prevents sudden build-up of torque surges, and contributes to smoothness of operation, particularly noticeable when rocking a car in low forward, or reverse, out of a soft traction spot.

The cooperative action of the control system of Figures and 6 is, of course, involved in this overall smooth drive, transition eiect, discussed in this specication separately.

The annular piston 129 is recessed in the cylinder space 133 of the casing 99, guided on pins 65 and held against rotation forces.

Brake release springs 66 are recessed in pockets 67 of piston 129 and are retained by annulus disc 68 held against leftward motion by lock ring 68.

Axial holes 69 in the web 99e of casing 99 drain oil from space 70 back to the main transmission sump S. Oil pressure is supplied to cylinder space 133 behind piston 129 by means of a passage 127 (see Figure 5), as will hereafter be more fully explained.

In Figure 3 the band 170 is self-sprung to clear the drum 14, and is supported in casing 99 by adjustable anchor 280, and actuated at the movable end 281 by rod 282 fixed to piston 160, sliding in the cylinder 159. The central web member 159e of cylinder 159 separates space 284 from space 285. Piston 160 moves upward under influence of fluid pressure fed to space 286 through passage 158.V

Under neutral control, there is no servo pressure applied to the front unit cylinder space 286 and spring 287 acting through member 298 bearing upon web member 159g secured to stern 293 Jforces stem 293 and piston 160 downwardly to yieldably bias the piston 160 in brake-releasing position. Under either forward or reverse setting of manual Valve 100 of Figures 5 and 5a, line pressure from pump line 115 is delivered via ports 106 and 197 to line 120 and to line 158 acting upward upon piston 160, to apply band 170.

Compensator pressure, derived from pressure varied and controlled by the accelerator pedal 400 through the compensator valve 380 of Figures 5 and 5a, is fed via passage 392 to space 288 to augment the pressure below piston 160, which compensator pressure varies with throttle advance, so that the band 170 is variably loaded to maximum under heavy torque demand as explained hereafter.

Brake releasing pressure is fed from line 139 to space 285 to counteract that of line 158 acting on the underside of piston 160, and passes through ports 291 to the passage 292 in hollow stem 293, and out through ports 294 to apply a thrust on the upper face of piston 283 (see Figure 3). Piston 296 fixed to rod 282 is held downward in space 288 by spring 297 retained by piece 298. The combined effective areas of pistons 160 and 283 is greater than that of pistons 296 and 160, hence the pressure in line 139 acts to release band 17 0.

ln Figure 4 the rear unit brake band 40 is self-sprung to normally be released from drum 31 to prevent drag of the band on drum 31 when fluid pressure is admitted to the band operating servo for band release actuation, and is held by adjustable anchor 302, and movable strut 303, loaded by rocker 384 is moved clockwise by the thrust of piston rod 305, of piston 201. The piston 201 is of two-step form. The central web 306 of the cylinder 200 is equipped with a check valve 307 of blade type, operable by plunger 308.

The main line pressure for releasing the normally applied rear unit band is furnished by line 121 to space 310, and by line 121e to the left of the check valve 307 to enter space 311 so as to apply a rightward thrust to piston 312. he latter is loaded by brake-applying springs 313. The skirt of the piston 312 at the right, slides outside of spring retainer cap 315, the springs 314 bearing against the rear face of piston 312. A tubular portion 316 of piston 312 extends to the left as a thrust spacer element, bearing against piston 201. Buffer spring 321 prevents slamming of 316 against piston 201. Spring 322 is fastened to travel with piston 201 and abut the web 306 at a given travel point to add `the spring resistance to the rightward motion of piston 201 when the brakereleasing force is fed to line 121.

` space 317 to thrust piston 201 to the left, and to act in space 318 `to augment that thrust. Piston 201 acts against spring 322 when uid pressure is admitted to chamber 310 by way of passage 121.

The pump supply system of the invention is worthy of brief examination. In Figure 3, the feed passage 185 leads from the pressure space of valve 180 to the interior of drum 3 of Figure 1, to maintain the working space W of the fluid flywheel 22-23 filled. The rearward projection of hub 24 (Figure l) is fitted with a novel form of valve 91, having extended radial lip 92 on the folded portion, of greater net effective area than the forward portion on which spring 93 seats. Rise of pressure in the working space W acts differentially on the lip 92 and on the folded portion, against the force of calibrated spring 93, to slide valve 91 to the left at a given pressure, and expose the ilow space 94 between the hub and the forward end of shaft 21 open to the longitudinal space between shafts 21 and 25. Fall of working space pressure permits spring 93 to seat valve 91 against the end of shaft 21.

The oil passing through the valve 91 to the space between the shafts is delivered to lubricate the running transmission elements through passages indicated at 96, 97 in Figure l and at 98, 98', 197 and 198 in Figure 2. This oil is at a measurable pressure at all times due t0 the constant feed of the pumps P and Q of Figure 5 as well as the additional working space pressure generated by the rotors 22 and 23; hence the oil body is passing through the system at sufficient replacement speed to equalize the temperatures of the whole drive assembly. PumpQ is driven by the vehicle tail shaft. The spent oil falls into sump S which lies under the whole transmission mechanism, and by its large area provides heat radiation from the oil outside of, as well as inside of screen 410, from which the pump suction lines 388 and 389 of Figures l and 2 draw. Sludge plug 393 permits removal of dirt from the sump pan S without dropping the pan. A certain amount of heat removal occurs through the wall of drum 3, from the body of oil being pumped to the working space, to the air body circulated in the flywheel housing. There are therefore two heat flow areas, one, the sump pan S, the other, the drum 3, which serve to cool the oil prior to the heating effect of the fluid flywheel circulation around the space W.

While it is appreciated that forced feed lubrication systems for transmissions are old, and that cooling means for such forced feed lubrication are also old, it is believed that the particular arrangement of the applicants invention in this respect, possesses features of novelty in stabilization of the temperature of the ycirculating oil body, in immediate transfer of the heated oil to the lubrication ducts for reducing the friction drag of a cold start, and in the making use of the sump pan and the enclosing drive drum for the rotor elements as radiators in the flow sequence described.

The gear train combination of the front and rear units with the fluid flywheel 22-23 and the reverse gear group provides four forward speed ratio ranges by actuation of the friction torque sustaining elements, brakes and clutches in the following pattern, the notation X indicating actuation.

Front Unit Rear Unit Brake Clutch Brake Clutch In the lowest ratio, the front unit brake 170 is applied by fluid pressure in kcylinder 159 beneath piston 160 for actuating piston loll, while the rear unit brake 40 is applied by the force of springs 3];4, 322 augmented by pressure in space 3ll7 acting on piston 201. r:The carrier 20 of the front unit is the power output member, and transmits drive in the reduction ratio of the front unit through the fluid ywhee 22u23 to the input power member, sun gear 26 of the rear unit, when annulus gear 27 is held by band 4G. The fluid flywheel 22-23 couples the two units at the variable slip ratio determined by the torque of shaft 21 and the speed of hollow shaft 6.

In second speed ratio, brake 170 is released while clutch 165 loo is being engaged to set up a 11 locking couple in the front unit, the hollow shaft 21 now driving impeller rotor 22 at engine speed. The drive train in low and second is a series drive, front unit to rear unit, as coupled by the fluid flywheel 22-23.

For drive in third, the front unit clutch 16S- loo is released and band 70 re-applied, and the rear unit brake 4l) released while clutch M7-163 is actuated. The drive train now divides the torque of hollow shaft 21, one component being sustained by the fluid `flywheel LZ2-23, and the other by clutch lt-lod In the rear unit these torque components are combined, the first being delivered by sun gear 26, and the second by annulus gear 27 to drive output-connected carrier Sti forwardly.

Drive in fourth gear is obtained by release of brake 170 of the front unit while actuating clutch 165-466. The torque of the engine on hollow shaft 2l is divided, one fraction being delivered by fluid flywheel 22f-23 t0 sun gear 26 at a speed averaging between 3 to 5 percent differential to that of the annulus gear 27 which rotates at engine speed.

In the first to reverse transition, the following pattern of actuation occurs:

The carrier 52 of the reverse unit being connected to the load shaft 59, and the annulus gear 27 of the rear unit connected by radial web 5l to the reverse unit sun gear 55, the application of engine torque at a torque multiplication to central shaft 25 and to rear unit sun gear 26 first furnishes a backward rotation component to annulus gear Z7, since the rear unit carrier 3@ is stopped or at low rotational speeds. With reverse unit annulus gear 57 stopped by cone i3d, the reverse component applied by reverse unit sun gear 55 causes planets 54 to roll around the annulus gear 57 in reverse direction, applying reverse torque to reverse unit carrier 52. As soon as reverse rotation of shaft Si) occurs, the rear unit carrier Sti partakes of the reverse rotation and the full reverse ratio of the combination becomes effective. The fluid flywheel 22- 23 furnishes all of the reverse drive torque.

The above rst-reverse-first shift pattern suggests that it would be extremely simple to negotiate this change directly; and rock a Car out of a soft traction area, but, as will be understood further below, in changing from first to reverse, the front unit brake 17o is not Vcontinuously held engaged, but is actually released and re-engaged after reverse cone 13G is seated, and this interval is controlled by a timing valve E50, which compels this unusual form of operation. The return shift from reverse to low is, however, obtained by leaving brake E70 engaged, and by the releasing of cone 13) while brake 4i) is being actuated.

As will be understood further, this transition shift for initial motion of the car from zero speed to forward or reverse may now be negotiated under controlled variable torque conditions, and the degree of torque reaction sustaining force made etective for the transition and drive intervals, is completely regulated and graduated by the controls, so that under no drive circumstances will there by any sudden jerks or lurches of the drive, nor any positive drive shocks or ratcheting action such as experienced with toothed pawl mechanisms.

The embodiment of the present disclosure includes a positive jaw or toothed brake pawl member 236 for the drum 5S of reverse unit annulus gear 57, but it is not used to establish reverse drive torque reaction. The pawl 236 is pivoted to lock teeth 62 against rotation and is actually spring pre-loaded for such action when the control for actuation of reverse cone 13o is set to establish reverse drive, yet is not utilized as a reverse drive brake. Only when the engine stalls, and the vehicle is at or near standstill, is the pawl 236 automatically engaged. This action is described in full in :connection with Figures ll and l2, and contributes substantially to the safety of vehicles in operation on mountain roads. if the engine stalls, front pump P no longer supplies servo pressure to load front unit brake 70, and the latter will be released by its springs 237, 297. Also7 if the car is at or near standstill, the rear pump Q cannot supply the deficiency at low or zero speeds. However, the fall of line pressure also releases brake 4o of the rear unit from its holding-off pressure, and springs 322 and Blf-i apply it to the drum 3l of annulus gear 7.7. lf at that interval, the re` verse unit annulns gear 57 is locked by pawl 236, the coupled elements of the rear and reverse units provide a safety brake effect sufiicient to prevent a car from drifting backward downhill, for example, likewise effective to prevent forward drift downhill, as will be understood from study of the drive connections.

To understand this acation, it is useful to remember that the carriers 3G and 52 of the rear and reverse units are fixed to the shaft 50. A rotational force coming from shaft Sti will endeavor to force planets 28 to roll around the annulus gear 27 held by brake lill, and if such motion be permitted, spin the sun gear 26 at overspeed in the same direction. However, with sun gear 55 of the reverse unit also stopped by brake do, and annulus gear 57 stopped by pawl 236, the locking couple thus established in the rear unit will prevent rotation of carrier 52 and shaft Sil. There is, therefore, automatic, positive braking of the vehicle motion, rendering it impossible for a car to run downhill out of the control of an inexperienced driver.

Now if the engine be stalled, as with a weak starting battery in cold weather, the need for a towing start must be considered, At a given road speed, rear pump Q delivers a line pressure to the servo system. Since brake 4t) of the rear unit is always engaged by its springs 322 unless lluid pressure is supplied to hold it disengaged, it

is only necessary to consider what energization control pattern is required to cause a friction member of the front unit to be actuated.

The governor G of Figures 5 and 6 will operate to provide a metered pressure to the spaces Zilli, and 26g of the shifter valves ifi-3, Md and 11b/i5 shown in Figure 5b, at its normal speed calibrations, and therefore at about 12 miles per hour, with the manual valve lo() of Figure 5 set for forward automatic drive, will cause the lst to 2nd shifter valve E43 to rise and deliver line pressure to actuate clutch lod-loo of the front unit, when the drive will be in second speed ratio. lf the output of pump Q is so controlled by the regulator' valving i3@ and T187 of Figure 6, that its net effective pressure and capacity are below the values needed to establish second speed ratio, the operation ot' coupling to the engine may be obtained at about 18 miles per hour, when the governOr pressure is sufficient to move the 3rd and 4th shifter valve 145, and cause actuation of both of the front and rear unit clutches.

The structures diagrammed in Figure 5 are the actureste alor and control devices and units for the ratio-establishing friction members of Figures 1 to 4, and the control mechanisms and valving required for their proper operation. The cut-away sections of clutches 165-166 and 167-160 are duplicates of the Figures 1 and 2 showings and the ratio servo brake actuator mechanism sections reproduce those of Figures 2, 3 and 4. The pump P of Figures 1 and 3 is shown in the lower left corner of Figure 5 and pump Q of Figure 13 in the lower right corner, with the governor G.

In the center of Figures 5 and 5b, the right-hand control panel includes the shifter valving which directs the pump pressure to the servo clutch and brake actuating mechanisms, and the pressure-responsive elements act ing as control servo operators for the shifter valving. The left-hand center panel of Figure 5 and Figure 5a shows a manual control valve 100, a cooperating timing valve 150, a pressure-regulating valve 350 operated by the engine speed control mechanism controlled by the accelerator pedal, a compensator pressure control valve 380 subject to variable pressure applied by the accelerator operated valve 350, a double-transition valve 250 also subject to variable pressure applied to it for obtaining a ratio pressure directing and inhibiting effect, and various pressure-area thrust plugs and Calibrating springs, described further below, in connection with the outlined control and actuating pressures.

Pressure for operating the servo mechanisms as distinct from the control pressures, is supplied from pump main 115 through lines 115 and 347 to ports 205, 214 and 203m (see Figure 5b) of the shifter valves 143, 144 and 145 which slide vertically upward in the valve body bores, from the positions shown, to connect the servo ports 214, 205 and 203a, respectively to the servo delivery lines 21o', 149 and 365. Specifically, line pressure is fed to port 205 of shift valve 143 by way of line 115, and branch line 118. Pressure is fed to ports 203e and 214 of valves 145 and 144, depending upon the position of manual valve 100, by way of line 115, branch line 117, line 119, and line 374 (see Figure 5). The shifter valves in the lower positions shown vent the servo ports at exhaust ports 217, 213 and 219, respectively, shown in Figure 5b.

Springs 212, 204 and 220 tend to hold the shifter valves in the exhaust positions, and plugs 203, 211 and 221 are moved upward against the spring force by governor-supplied pressures to the lower spaces 202, 210 and 209 by passages 178 and 179, of Figure 5b.

Shifter valve 143 delivers pressure for establishing the upshift from low to second and is noted as the 1st to 2nd shifter. Similarly valve 144 is the 2nd to 3rd shifter and valve 145 the 3rd to 4th shifter.

At the upper end of the valve body is located a set of control plugs, the plug 140 acting against spring 204, the plug 141 against spring 142 and the plug 222 which may be moved to contact the upper extremity of the stem of valve 145. A variable `control pressure is made available by the valving of the left hand panel, to move the plugs 140, 141 and 222 against the springs 204, 142 and against the stem 0f valve 145 to oppose the forces applied by the governor plugs 2'03, 211 and 221 tending to upshift the shifter valves.

It will be understood that assuming a speed-responsive pressure rising with speed is made available to the governor plug spaces 202, 210 and 209 to move the shifter valves upward against the springs 204, 212 and 220, the springs may have a designed set of rates suc-h that valve 143 will rise first, at a given governor pressure, since spring 204 is of a rate to permit the action at a relatively low pressure; then valve 144 will next rise, and finally valve 145, so as to cause ratio upshift from first to second, to third, and then fourth.

In order to provide the driver with some means to delay this upshift action of the governor, and compel the vehicle speed to rise to higher ranges before the upshift sequence of ratio steps is negotiated, the variable pressure applied above plugs 140, 141 and 222 is derived from a control valve 350 which is moved in accordance with the power rdemand made by the driver in advancing the engine accelerator pedal. This arrangement enables the automatic ratio controls to be calibrated for a normal speed controlled shift pattern in which the ordinary and normal accelerator pedal motion is related to the effective speed shift points for the governor pressures, so as to obtain an economy type of engine operation in which the upshifts occur over a range of governor speeds with respect to engine speeds. This permits the drive to operate in the higher transmission ratios, for longer periods, so that for a given set of tratiic on road circumstances, at selected car speeds during a measured time, the engine R. P. M., is at an optimum for fuel economy.

For drive intervals in which the driver wishes to overcome the normal economy calibration equilibrium of the controls, and set aside economy operation in favor of acceleration and performance, advance of the accelerator pedal to maximum range increases the downshift pressures acting on plugs 140, 141 and 222, so that the engine is speeded up to higher torques and speeds for given car speeds.

TRANSMSSON AND FLUID PRESSURE CONTROLS Reverse shift control The control diagram of Figure 5 shows a special new form of manual valve which performs novel functions in reverse gear setting. The regular drivers steering column control linkage moves the valve 100 to the 11, L, D, N positions as indicated in Figure 5a.

Manual vulve and port/'ng The ports of manual valve 100 are numbered in order from top to bottom 101 to 110.

Pump delivery lines The pumps P and Q deliver via lines 196 and 81 through check valve 111 to the pump line 115, branched at 116 for the governor; at 117 to valve port 107; and at 118 to the feed port 205 of the 1st to 2nd shifter valve.

Line 117 has a side branch 119 connected to valve ports 102 and 103.

Manual valve structure As indicated in Figure 5, the valve 100 has end closure boss a, intermediate bosses b, c and d, and a reduced upper end boss of tapered form e, which also serves as an exhaust relief pass since its cylindrical dimension is less than that of the bore for valve 100.

As shown in Figure 5a, pump line pressure enters port 107 and may exit at port 105 to line 120 leading to the inlet port of timing valve 150.

Rear unit brake hold-Ot action Pressure from branch line 119 in port 102 is dead ended, but that in port 103 may pass between bosses d and c of valve 100 to port 104 and to line 121 leading to the left end of the rear servo cylinder 200, to deliver release pressure to the rear unit brake pistons 201 and by 121e to move piston 312.

Shift prevention pressure The branch 122 of line 121 connects to the lower end of the bore of the double transition valve 250.

The pressure admitted by line 117 to port 107 also passes downward to ports 108 and 109.

That in port 108 goes by line 123 to the port space 142e between the 2nd to 3rd regulator plug 141 and the 2nd to 3rd shift valve 144, and by line 124 to the end space 217 for the 1st to 2nd regulator plug 140, for reasons explained later.

Pressure in port 109 passes by line 125 to the bladetype check valve 126 (see Figures 5 and 5c) and by line 127 to the cylinder port 128 for reverse unit piston 129,

1-1 to move same against spring 131 and apply the cone surface of 129 against the reverse cone 130 and clamp same to the xed cone 132. The cylinder space is 133.

Timing valve Before this action can occur, the action of the timing valve 150 needs consideration.

As shown in the drawing, spring 151 as in the Figure 5 and 5a views of 150, is holding the valve 150 to the right.

Valve 150 has a hollow end boss F, a ccnt'al g and a reduced diameter boss l1, as shown in detail in Figures 7, 8 and 9.

Inactive setting-gure 9 In other than reverse setting of the manual valve ith?, the boss d of valve 100 moves valve 15% against spring 151, farther 'left than shown in the Figure 5 view of 1513, and in reverse setting the force of spring 151 acts as shown in the Figure S View. The Figure 7 view shows valve d in metering position.

The ports for valve 150 are from left to right 153, 154, 155 and 156.

Pump line pressure in line 120 and port 155 cannot perform any 'direct action on valve 15() since bosses F and g are of the same diameter. Boss g has a slight taper portion g at the right where it intersects port 156.

Initial valve action The delivery of reverse servo pressure to line 125 also delivers to branch line 134 leading to port 156 where the slight differential area at g permits a small pressure force to tend to move valve 151i to the left against spring 151.

lt will be noted that at this time, with valve 150 in right hand position, the front servo feed line 15S is not connected to the pressure feed port 155, being blocked by boss F, and is connected so as to bleed to exhaust port 153 by passage 157 (see Figure 5a).

The movement of manual valve 161i to the reverse setting of Figure 5 delivers pump line pressure to line as noted above, and there is a time interval of filling of the cylinder space 133 of the reverse cone piston 129, at the end of which the rcliection of the resistance of springs 131 results in a measured rise of pressure in branch line 134iand port 156. This starts valve 159 to move left against spring 151, completely closing exhaust port 153, and opening port 154 to pressure feed port 155. The resulting delivery to front unit servo line 158 is felt by piston 169 in servo cylinder 159, and the front unit band 170 is applied.

Timing valve action The timing action of valve 154i prevents the front unit band 17) from being applied until after the reverse servo piston 12%` is properly applied to stop the reverse unit reaction member 130. This timing action assures that there will be no torque reaction bumping noises, contributing to smoothness of operation, such that it now becomes relatively easy for the `driver to rock the car in reduction forward and reverse without shock and without abuse of the mechanism. Valve 150 serves another purpose to be described below.

Upon shift from reverse to low, the nose e of valve 10@ strikes the end boss /i of valve 15G, compresses spring 151 and puts the valve in a position farther left to that of the Figure 9 view, so that this moves the valve 151i to the exhaust shut-o position for ports 154 and 153, and the spring 151 is fully compressed.

Metering valve action The upper half Figure 5a shows the valve 15th with valve boss F near the right edge of port 154, so'that a slight rise of pressure in port 156 may provide a slight feed to port 154 and servo line 158. At the same time, the lower left end of boss F has been moved to seal eti exhaust at port 153, and the existing pressure in port 154 is transferred by passage 157 to the left face of valve 150, tending to assist the spring 151, and build up a force tending to close off feed from 155 and 154, and expose ports 154, 157, 152 to drain at 153. This metering action of pressure from 155 to servo line 158 acts continuously after the rise of control pressure in port 156 has signaled that the reverse cone piston 129 has seated, and consequently the variation of line pressure in 155 is paralleled and repeated in servo line 15S during the period when brake piston 16% is applying the band 170 of the front unit.

Check valve operation The check valve 126 of Figure 5 is of uncommon nature and provides a pressure response effect of particular utility in the providing of control pressures in all of the lines where pressure variation is needed for smooth operations.

As shown in Figure 5c, the valve casing 136 shown in section has an orifice 133 at the point of entry of line 125, and the blade valve 126 has an orice 137 of smaller dimension than that of orilice 13S. The diameter of orifice 137 is preferably one-half that of orice 138. The lleXible blade 126 is fulcrum-pinned to a projection of the casing 136, and its spring action is calibrated to yield at a predetermined pressure from line 125.

When the initial rise of pressure in line 125 occurs, the quantity of oil per unit time flowing through to line 127 is regulated by orifice 137 in the blade 126 a small amount, the action permitting a measured rise of pressure in 125 and in the other lines such as 134 and 122. At a given pressure, the blade 126 is exed open by the pressure, and the effective larger oriice 133 now controls the rate of lling of cylinder 133. This action causes a momentary line pressure drop during the filling interval, so that timing valve 1511, for example, is unable to feed servo pressure to front unit cylinder 159, to apply band 170, since the control pressure in port 156 is not high enough to overcome spring 151.

As will be noted by reference to Figures l0, 1l and l2, the parking brake pawl member 236 is spring biased when the manual valve is placed in reverse to tend to cause teeth 238 to engage teeth 62 of drum 58 to provide a vehicle parking brake. Pawl member 236 is, however, prevented from moving to cause teeth 238 and 62 to engage by means of blocker piston 241) (see Figure l1) which is caused to move outwardly against the action of spring 241 by action of fluid pressure admitted behind the piston through line 116 (see also Figure 5). It has been found that in the absence of valve 136, the pressure requirements of the reverse cone actuating cylinder may be such (particularly at low vehicle and engine speeds) as to cause a pressure drop in line 116 sucient to permit the parking brake to be prematurely engaged. Check valve 136 restricts the initial rate of build up of pressure in chamber 133 of the reverse cone piston, thereby preventing unduly rapid pressure drop in line 116 and preventing this undesirable premature engagement of the parking brake.V With this arrangement, the parking brake may not be engaged until the vehicle motion is stopped and the engine turned off so that neither the front nor rear pumps supply pressure to line 116.

The rise of control pressure in branch line 134 is also provided in the extension of line leading downward to the control plug assembly for the front unit pump P.

Regulator valve 189 ofFigures 3 and 5 has small boss e, larger boss j and an end plug k serving as a spring retainer and a thrust member.

The pump housing 181 is ported at 182 to communicate with the pump delivery passage and at port 184 is connected to deliver pressure to line 185 leading to the fluid ywheel working space W, and connected at 186 

